1. Field of the Invention
The present invention relates to a surface-mount antenna incorporated in a communication apparatus, such as a portable telephone, and relates a communication apparatus using the surface-mount antenna.
2. Description of the Related Art
FIG. 16 shows one example of a surface-mount antenna incorporated in a communication apparatus, such as a portable telephone. A surface-mount antenna 1 includes a dielectric substrate 2 in which a radiation electrode 3, a ground electrode 4, and a feed electrode 5 are formed on the surface thereof. The radiation electrode 3 is formed over side surfaces 2a, 2b and 2c of the dielectric substrate 2. The ground electrode 4 is formed on the entirety of a side surface 2d of the dielectric substrate 2 so as to establish electrical connection with the radiation electrode 3. The feed electrode 5 is formed on the side surface 2a so that a predetermined distance is maintained between the feed electrode 5 and the radiation electrode 3.
The feed electrode 5 is connected to a power supply 6. When the power is supplied from the power supply 6 to the feed electrode 5, the radiation electrode 3 is supplied with the power by means of capacitive coupling from the feed electrode 5. When the supplied power drives the radiation electrode 3, the surface-mount antenna 1 transmits or receives electromagnetic waves in a single predetermined frequency band.
A 900 MHz band and a 1.9 GHz band are currently used as operating frequencies for portable telephones.
When the communication apparatus is required to use two different operating frequency bands such as these, a single surface-mount antenna must transmit and receive the electromagnetic waves in the two different frequency bands. However, the surface-mount antenna 1 in FIG. 16 can transmit or receive the electromagnetic waves only in a single frequency band.